Trent Harris's The Beaver Trilogy (1980-1999) is a one-of-a-kind video which, among its many treats, unburies, from the '80s, some amazingly off-the-charts thespian performances by young Sean Penn and young Crispin Glover.

Part one of the trilogy: the year is 1980, and documentarian Harris comes across, one day on the road, a video natural: Larry Huff, 21. A manic gabber who drives a '64 Impala named "Farrah." Larry talks on and on about his beloved home town, Beaver, Utah, where he's well known, he says, for impersonations. "I'm the Beaver Rich Little," he brags, whose specialties are imitating Barry Manilow and Olivia Newton-John.

The documentary jumps to talent-show day at Beaver High, and to Larry putting on his Newton-John lipstick and blonde wig. Well, he looks more like an 18th century fop than the Australian chanteuse, but so what? The talent show: uproarious Americana, with flat-singing sisters, an exuberant teen Brenda Lee, high-kicking disco girls in boots, and Larry himself, doing an Olivia number then coming back for a Barry encore, some vile song about the rhythms of New York.

Good enough, but Part two is the incredible stuff: a Part one repeat, with an actor standing in for the documentary-maker ( a condescending one, who sneers at the amateurs of Beaver) and the great Sean Penn, soon after Fast Times at Ridgemont High, now playing Larry, and doing a riff off of the tape of Larry he's studied from part One. Penn's Larry is far more obviously disturbed than the cheery ball of energy we've already seen; the sad-clown depressive emerges. When the bewigged, big-boots Penn does his Olivia torch number in a grating, heartbreaking falsetto, the moment has Chaplinesque pathos, so funny and so Elephant Man-tragic at the same time.

Parts one and two are plenty! Videomaker Harris pushes on, however, to a third, more loosely fictive variant. Crispin Glover, the Larry recruit, does his characterization incorporating both the part-one "real" Larry and the Sean Penn-as-Larry. Part three is pretty good, but the brilliance of Sean Penn, so definitive, makes Crispin's vamping redundant.